1. Field of the Invention
The present invention relates to a connector for tubular truss assemblies. More specifically, the invention relates to a connector which forms a part of a truss cell wherein tubing interconnected between selected adjacent connectors is loosely held in the connector to facilitate shaping the truss assembly to desired contours and for distributing the forces and mechanical stresses existing throughout the assembly, to each member thereof.
2. Description of the Prior Art
The formation of truss assemblies using connectors of the prior art generally involves either the welding or bolting rigidly together of the constituent parts of the assemblies. Examples of such assemblies are shown in U.S. Pat. No. 3,596,950, U.S. Pat. No. 4,101,230 and U.S. Pat. No. 4,343,562. With the application of strong transverse forces on the truss assemblies described in the above patents the rigid welds tend to fracture or tear. The truss assemblies in the prior art generally will load the plate elements to which they are welded. Usually this loading is undesirable since it may easily lead to laminar tearing of the plate material.
Other connectors in the prior art provide rigid connectors incapable of contouring to form desired geometric shapes such as cylinders and semi-spherical or completely spherical domes. Examples of such connectors are described in U.S. Pat. No. 1,144,491, U.S. Pat. No. 3,563,580 and U.S. Pat. No. 4,076,431. In each case the resulting structure is limited solely to specific geometric shapes such as tetrahedral or fixed sloped roofs for portable car or boat storage.
The present invention remedies the deficiencies of the prior art. The connector includes a plurality of receptacles for receiving in a loosely fit fashion tubing which interconnects adjacent connectors. The truss assembly is maintained in a unitary structure by means of either securing the tubing to the respective connector or by means of truss wires connected to selected ones of adjacent connectors and biased to urge the interconnected connectors together. The structural members of the truss are held in position in compression in a loose fit fashion. This unique manner of loose coupling allows slight movement of expansion and contraction and the distribution and defocusing of forces throughout the truss assembly.
The loose coupling diminishes the potential of fracture and tearing characterizing the aforementioned connectors of the prior art. Since the forces are distributed throughout the truss assembly, the undesirable concentration of forces and stress is minimized. Because stress concentrations are minimized lighter and weaker structural tubing can be used.
Yet another unique feature of the loosely fitting coupling of the truss tubing and connectors is the ability to "turn corners" of the surfaces it forms to create a non-planar assembly either for functional or aesthetic purposes.
To form desired structural shapes such as a cylinder it is required to turn the plane of the face of the truss assembly by the slight shortening of the tubing on the inner side of the turn desired to be formed. Spheres, domes, squares, rectangular and composite truss cells such as hexagonal, octagonal and the like are within the contemplation of the present invention.
Moreover the loose fitting concept which is contrary to designs of the prior art provide for rapid assembly and disassembly. The truss once quickly assembled is less prone to the damaging effects induced by movement of the assembly because of the "forgiveness" inherent in non-rigid structures. Once assembled, parts of the truss assembly can be removed without collapse of the entire assembly. Thus alterations in design during assembly is possible without substantial breakdown of the entire truss assembly.